Soon after the first settlers arrived, entrepreneurs who knew the value of sawing timber and boards, as well as milling flour, built water powered mills along many of Ohio’s rivers, streams and creeks. This quickly changed the way barn timbers were converted. Since sawyers knew they could sell large amounts of small scantlings for rafters, girts and braces, they began sawing these materials to standard sizes. Timber framers found it very practical to transport material that was small on even the earliest wagon paths. Traveling to the mill by oxcart to purchase 4x4 brace stock was also something that could be done by young apprentices, while the experienced framers set about the business of hewing the larger timbers. As roads improved larger timbers could be hauled, and in some cases even large girts, posts and ties were framed from sawn stock.
The early water-powered mills were an asset to barn builders, but they were slow and limited to relative short logs. Thus, the barns built in these times exhibit hand-converted timbers for most of the principle members. The early mills were built on a principle called "up and down" sawing, also known as frame or sash sawing, since the saw blade was a straight piece of heavy steel mounted in a wooden frame. This frame would move up and down, while the carriage mechanism slowly moved the log through the frame. This method of milling left easily identifiable "saw tracks" that run straight, but slanted, across the face of the timbers as coarse parallel lines. Discovering barns that have both hewn and sash sawn timbers usually means they were built after the first sawyers arrived, but probably before the Civil War when a major change in saw milling technology occurred.
Developing enough horsepower to run a circular saw large enough to mill logs was difficult using water wheels or water driven turbines, but steam engines developed in the mid-19th Century were capable of running large blades at high speeds. These new mills could cut large diameter logs at higher feed rates and often were built to handle logs of greater length, although usually limited to 18' to 30' or so. Circular saw mills quickly replaced vertical mills in the mid-19 Century. A major change in barn construction resulted, since improved mills and improved roads meant timber framers could build barns more quickly and completely with sawn materials. This was done by making longer timbers from shorter sawn pieces "scarfed" together end to end. Some timber framers still chose to hew the longest pieces from logs 30’long and greater. The saw tracks from circular mills imprint large arcs across the faces of the timber. These are easily distinguished from those left by the up and down mills. Finding barns that include timbers exhibiting curved saw marks indicates they were built after the Civil War.